This doesn't make any sense, I'm afraid. That option has no effect on how what received iCalendar items look like (and should also have no effect on sending meeting requests through an Exchange 2000/2003 server).
What would be useful would be to see a raw incoming message with the iCalendar message part.

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Sue Mosher, Outlook MVP
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Microsoft Outlook Programming - Jumpstart for
Administrators, Power Users, and Developers
http://www.outlookcode.com/jumpstart.aspx
Exactly, it doesn't make sense to us either, which is why I'm posting it
here. Meeting requests will not work coming from an outside company unless
that checkbox is checked. By default it is greyed-out. To remove the gray and
check the checkbox, we have to create a new POP3 email account in Outlook.
There is nothing anywhere that explains this, and as I feared, it is even too
weird a problem for these forums.
> This doesn't make any sense, I'm afraid. That option has no effect on how what received iCalendar items look like (and should also have no effect on sending meeting requests through an Exchange 2000/2003 server).
>
[quoted text clipped - 19 lines]
> > our users, is there another way to UN-GREY-OUT the "When sending meeting
> > requests over the Internet, use iCalendar format." checkbox?
Diane Poremsky [MVP] - 11 Aug 2005 22:32 GMT
Let me make sure I understand.... when someone outside the company (such as
me) sends you a meeting request, you will receive it as plain text, unless
you add a POP account to your profile?
It makes no sense to me. The text in the body indicates it's being sent as
plain text, not RTF and the format is controlled by the sender and sender's
mail server.

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> Exactly, it doesn't make sense to us either, which is why I'm posting it
> here. Meeting requests will not work coming from an outside company unless
[quoted text clipped - 43 lines]
>> > meeting
>> > requests over the Internet, use iCalendar format." checkbox?
Sue Mosher [MVP-Outlook] - 11 Aug 2005 23:09 GMT
Can you get your hands on the raw incoming message?

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Sue Mosher, Outlook MVP
Author of
Microsoft Outlook Programming - Jumpstart for
Administrators, Power Users, and Developers
http://www.outlookcode.com/jumpstart.aspx
> Exactly, it doesn't make sense to us either, which is why I'm posting it
> here. Meeting requests will not work coming from an outside company unless
[quoted text clipped - 6 lines]
>>
>> What would be useful would be to see a raw incoming message with the iCalendar message part.
>> > We're having a problem that I fear will not get resolved without an expensive
>> > call to Microsoft, but here it is for you to consider:
[quoted text clipped - 15 lines]
>> > our users, is there another way to UN-GREY-OUT the "When sending meeting
>> > requests over the Internet, use iCalendar format." checkbox?
Frank Schirrmeister - 22 Sep 2005 23:44 GMT
I have the same problem in reverse. Meetings sent from a machine with greyed
out icalendar setting arrive on my machine plain and are not recognized by
Outlook as a meeting (even though the option on the receiving end is set).
Here is a source.
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN">
<HTML>
<HEAD>
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1">
<META NAME="Generator" CONTENT="MS Exchange Server version 6.5.7226.0">
<TITLE>Canceled: Asia</TITLE>
</HEAD>
<BODY>
<!-- Converted from text/rtf format -->
<P><FONT FACE="Georgia">When: Monday, October 17, 2005 12:00 AM to Saturday,
October 22, 2005 12:00 AM (GMT-08:00) Pacific Time (US & Canada);
Tijuana.</FONT></P>
<P><FONT FACE="Georgia">*~*~*~*~*~*~*~*~*~*</FONT>
</P>
<BR>
</BODY>
</HTML>